Subclinical Thyroid Disease: A Clinician's Perspective

Every clinician knows the symptoms, signs, and laboratory abnormalities associated with overt hyperthyroidism and hypothyroidism. Both conditions are unequivocally associated with morbidity and, occasionally, mortality, and no one would dispute the importance of timely diagnosis and therapy. In contrast, subclinical hyperthyroidism and hypothyroidism have subtle clinical manifestations at most, and the importance of timely diagnosis and treatment continue to be contentious subjects of research studies, position papers, and editorials. The central issues are whether subclinical thyroid diseases are of sufficient clinical importance to warrant screening or case finding and whether, once these conditions are detected by an abnormal serum thyrotropin value and confirmed by further testing, therapy is justified. Because reliable thyroid-stimulating hormone (TSH) assays have been available for almost 20 years, one would think that adequate data would have been amassed by now to answer these questions definitively. However, this is not the case, and we continue to rely on small clinical studies, epidemiologic data, computer simulations [1], and clinical impressions rather than the results of large randomized clinical trials.

In this issue, Helfand and Redfern [2] have made an effort to develop guidelines to assist clinicians when they encounter patients with subclinical thyroid disease. Their recommendations for checking a serum TSH level in patients who come to physicians for other reasons are consistent with those of the American Thyroid Association [3] and the American College of Pathology [4]. Given the high prevalence of thyroid disease in women older than 50 years of age, case finding in this population may be justifiable. More problematic for Helfand and Redfern is what to do when subclinical thyroid disease is found. Unfortunately, their literature review is incomplete; thus, they did not incorporate pertinent clinical information that could have been brought to bear on the subject. I review their recommendations for …